Burglar-alarm



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.t s e H G INVENTOR- EDQRJOHNSON EDMIs'roN P. JOHNSON, OF DECATUR, ILLINOIS.

BURGLAR-AL ARM.

SPECIFICATION forming part of Letters Patent No. 621,419, dated March 21, 1899.

Application filed May 2, 1898. Renewed February 4, 1899. Serial No. 704,544. (No model.)

To all whom it may concern:

Be it known that I, EDMISTON P. JOHNSON, of Decatur, county of Macon, and State of Illinois, haveinvented certain new and useful Improvements in Burglar-Alarms, of which the following is a specification.

This invention is exemplified in the structure hereinafter described and it is defined in the appended claim.

In the drawings forming part ofthis specification, Figurel isahorizontal section through a fragment of door and door-casing, showing the alarm applied thereto. Fig. 2 is an elevation of a fragment of window-casing, showing the alarm applied thereto and also showing a fragment of sash in section. Fig. 3 is a section through the alarm, showing the same set or in an operative condition. Fig. 4 is a sect-ion lengthwise through the alarm, showing the movable parts thereof in the positions they occupy immediately after the alarm is thrown. Fig. 5 is a side view of the alarm, showing the cartridgefeed opening in the alarm-tube.

The alarm comprises a tubular body 1, having an opening 2 in its side to admit a detonating cartridge 11, and at one end of the opening 2 the bore of the tube is diminished to form bearings for the fiange of the cartridge. The diminished bore in which the cartridge rests is shown at din Figs. 3 and 4. At the opposite end of the tube the bore is diminished, as shown in the drawings, and the end Wall 5 provides a bearing for a catch 8 on the bar 7 of the exploding-plunger 6. The plunger conforms to the large internal bore of the tube 1. Its bar 7 extends through the end of the tube opposite the contracted bore 4. has the notch or catch 8, which engages wall 5 of the end of the tube, audit has a fingerpin 10, that protrudes sidewise through a slot 3 of the tube. It also has an impinging teat 6f onits forward or contact end, which strikes the rim of the cartridge and causes an explosion. A spiral compression-spring 9 fits around the bar 7 between the plunger 6 and the end wall 5, and such spring supplies the force needed to explode the cartridge. An

alarm to be used on a door is provided with a screw, as 12, extending from the side of the tube opposite the finger-pin, and this screw is set into the door-casing, as shown in Fig. l, leaving the end of the tube flush with the casing and out of the way of the swing of the door. When ever it is desired to set the alarm, the plunger is forced against the spring by pressure applied against the finger, and the bar 7 is moved outward until its catch engages the wall 5. This brings the bar into the path of the door, and when the tube is supplied with a cartridge inserted through opening 2 and placed in the diminished bore 4 the alarm is ready for action. When the door 13 is opened far enough to force the bar from contact with the catch, the spring will carry the plunger against the cartridge with sufficient force to cause an explosion, alarming the person opening the door and giving notice to the inmates of the house of the attempted entrance.

When the alarm is to be applied to a Window, it is made with a screw projecting at an angle of ninety degrees with the finger-pin, and such screw is set into the window-casing 15 in Fig. 2 in position for the bar 7 to protrude into the path of the window-sash 1i. An attempt to raise the window will detach the bar and cause an explosion, as hereinbefore explained.

The notch 8 in bar 7 is in the side opposite the finger-pin, and the pressure on the pin tends to force the catch into engagement.

An alarm constructed in accordance with the foregoing description is cheap and simple.

It provides an effective safeguard against burglars, and it is not in the way when out of use.

What I claim is In a burglar-alarm, the combination of the tube 1 having opening 2, slot 3, contracted bore 4, end wall 5 and screw 12, the plunger 6 in the tube, the bar 7 on the plunger having the catch 8 adapted toengage the end 

